The rate of the total nitrogen excretion by Nereis diversicolor Muller was studied. It was shown that this value correlates with body weight and is described by functional equation N = 0.82*W^0.63, where W - dry body weight, N - nitrogen excretion in mg/day. The relation between the rates of nitrogen excretion and oxygen consumption was expressed by equation N/Q = 0.078*W^-0.1. Our analysis of the data in literature shows that the correlation between nitrogen excretion and body weight exists also in all Vermes phylum. This suggests that the above mentioned correlation is manifested in animals regardless their belonging to different systematic position and age groups.